Expert Point of View: Anthony V. D’Amico, MD, PhD


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“Thirty-six months of hormone therapy is the standard of care for the treatment of high-risk prostate cancer treated with radiotherapy,” said formal discussant Anthony V. D’Amico, MD, PhD, Professor in the Department of Radiation Oncology at Harvard Medical School and Chief of Genitourinary Radiation Oncology at Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston.

In order to establish whether 18 months vs 36 months of therapy is truly comparable, a noninferiority trial is needed with a defined upper boundary of the confidence interval for the hazard ratio, Dr. D’Amico continued. “Noninferiority does not mean equivalence. We need to determine what is acceptable to establish noninferiority,” he said.

“The present trial was designed as a superiority trial, but should have been designed as a noninferiority trial. The confidence interval is wide (0.83–1.59), and with data presented at this time, the upper boundary could represent a 59% increase in death,” he told listeners.

Longer Follow-up Needed

Using an exponential model based on current death rates, it would take 8.5 years to determine whether 18 months is superior. “What we can say using rigorous criteria is 36 months is not superior to 18 months, but 18 months may still be inferior,” he reasoned.

“Over longer-term follow-up, this study will ascertain if 18 months can be substituted for 36 months, if we use the same benchmark. Right now, for high-risk patients treated with 70-Gy radiotherapy, 36 months of hormone therapy may be too long, 6 months is too little, and 18 months may be just right. But longer follow-up is needed to make that statement,” he concluded. 

 “Thirty-six months of hormone therapy is the standard of care for the treatment of high-risk prostate cancer treated with radiotherapy,” said formal discussant Anthony V. D’Amico, MD, PhD, Professor in the Department of Radiation Oncology at Harvard Medical School and Chief of Genitourinary Radiation Oncology at Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston.

In order to establish whether 18 months vs 36 months of therapy is truly comparable, a noninferiority trial is needed with a defined upper boundary of the confidence interval for the hazard ratio, Dr. D’Amico continued. “Noninferiority does not mean equivalence. We need to determine what is acceptable to establish noninferiority,” he said.

“The present trial was designed as a superiority trial, but should have been designed as a noninferiority trial. The confidence interval is wide (0.83–1.59), and with data presented at this time, the upper boundary could represent a 59% increase in death,” he told listeners.

Longer Follow-up Needed

Using an exponential model based on current death rates, it would take 8.5 years to determine whether 18 months is superior. “What we can say using rigorous criteria is 36 months is not superior to 18 months, but 18 months may still be inferior,” he reasoned.

“Over longer-term follow-up, this study will ascertain if 18 months can be substituted for 36 months, if we use the same benchmark. Right now, for high-risk patients treated with 70-Gy radiotherapy, 36 months of hormone therapy may be too long, 6 months is too little, and 18 months may be just right. But longer follow-up is needed to make that statement,” he concluded. 

 “Thirty-six months of hormone therapy is the standard of care for the treatment of high-risk prostate cancer treated with radiotherapy,” said formal discussant Anthony V. D’Amico, MD, PhD, Professor in the Department of Radiation Oncology at Harvard Medical School and Chief of Genitourinary Radiation Oncology at Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston.

In order to establish whether 18 months vs 36 months of therapy is truly comparable, a noninferiority trial is needed with a defined upper boundary of the confidence interval for the hazard ratio, Dr. D’Amico continued. “Noninferiority does not mean equivalence. We need to determine what is acceptable to establish noninferiority,” he said.

“The present trial was designed as a superiority trial, but should have been designed as a noninferiority trial. The confidence interval is wide (0.83–1.59), and with data presented at this time, the upper boundary could represent a 59% increase in death,” he told listeners.

Longer Follow-up Needed

Using an exponential model based on current death rates, it would take 8.5 years to determine whether 18 months is superior. “What we can say using rigorous criteria is 36 months is not superior to 18 months, but 18 months may still be inferior,” he reasoned.

“Over longer-term follow-up, this study will ascertain if 18 months can be substituted for 36 months, if we use the same benchmark. Right now, for high-risk patients treated with 70-Gy radiotherapy, 36 months of hormone therapy may be too long, 6 months is too little, and 18 months may be just right. But longer follow-up is needed to make that statement,” he concluded. ■

Disclosure: Dr. D’Amico reported no potential conflicts of interest.


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